Isobutyric ester compound having propanoyloxy group at alpha-position, fragrance composition, and use thereof as fragrance

ABSTRACT

A fragrance composition comprising a compound represented by Formula (1) as an active ingredient: 
     
       
         
         
             
             
         
       
     
     wherein, in Formula (1), R 1  represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

TECHNICAL FIELD

The present invention relates to isobutyric ester compounds having a propanoyloxy group at the α-position, fragrance compositions, and use thereof as a fragrance composition.

BACKGROUND ART

Some isobutyric esters are known to be compounds useful as fragrances. For example, Non Patent Document 1 describes that various isobutyric esters are mainly used as flavors, and all these isobutyric esters are flavor materials having a fruit scent; specifically, methyl isobutyrate gives a sweet apricot-like scent, propyl isobutyrate gives a strong pineapple-like scent, butyl isobutyrate gives a fresh apple- and banana-like scent, and isoamyl isobutyrate gives a sweet apricot- and pineapple-like scent.

Additionally, Patent Document 1 discloses that, as an isobutyric ester having a bond with oxygen at the α-position, a linear or branched alkyl ester having 4 to 12 carbon atoms of α-alkoxyisobutyric acid is useful as a fragrance, and n-hexyl α-ethoxyisobutyrate has a lavender-like aroma.

On the other hand, Non Patent Document 2 describes that methyl α-propanoyloxyisobutyrate is obtained by methylating an oxidized product of a specific furanone compound with diazomethane, but there is no description about the aroma characteristics thereof, fragrance compositions comprising the same, and further, methods for use as a fragrance.

CITATION LIST Patent Documents

-   Patent Document 1: U.S. Pat. No. 3,368,943

Non Patent Document

-   Non Patent Document 1: “Gousei Koryo: Kagaku to Shohin Chishiki,     zoho shinban (Synthetic fragrance: chemistry and product knowledge,     new enlarged edition)”, The Chemical Daily Co. Ltd., 2016, pp. 580     to 582 -   Non Patent Document 2: Canadian Journal of Chemistry, 1984, vol. 62,     pp. 2429-2434

DISCLOSURE OF THE INVENTION Technical Problem

An object to be solved by the present invention is to provide an isobutyric ester compound having a propanoyloxy group at the α-position, useful as a fragrance and a fragrance ingredient. Further, another object to be solved by the present invention is to provide a fragrance composition containing an isobutyric ester compound having a propanoyloxy group at the α-position as an active ingredient and use of the compound as a fragrance.

Solution to Problem

The present inventors have synthesized various compounds and have made a diligent research of the aromas thereof. Thus, the present inventors discovered that particular ester compounds of isobutyric acid having a propanoyloxy group at the α-position are useful as fragrances and fragrance ingredients.

That is, the present invention is as follows.

<1> A fragrance composition comprising a compound represented by Formula (1) as an active ingredient:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

<2> The fragrance composition according to <1>, wherein, in Formula (1), R¹ is selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.

<3> Use of a compound represented by Formula (1) as a fragrance:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

<4> The use according to <3>, wherein, in Formula (1), R¹ is selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.

<5> The use according to <3> or <4>, wherein the compound represented by Formula (1) imparts a mint-like scent.

<6> The use according to <3> or <4>, wherein the compound in which R¹ is an isopropyl group in Formula (1) imparts a damascone-like fruity-tone, floral-tone, or woody-tone scent.

<7> A compound, represented by Formula (2):

wherein, in Formula (2), R² represents a linear, branched, or cyclic alkyl group having 2 to 5 carbon atoms.

<8> The compound according to <7>, wherein, in Formula (2), R² is selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.

<9> The compound according to <7> or <8>, wherein, in Formula (2), R² is an ethyl group.

<10> The compound according to <7> or <8>, wherein, in Formula (2), R² is a n-propyl group.

<11> The compound according to <7> or <8>, wherein, in Formula (2), R² is an isopropyl group.

<12> The compound according to <7> or <8>, wherein, in Formula (2), R² is a n-butyl group.

<13> The compound according to <7> or <8>, wherein, in Formula (2), R² is an isobutyl group.

<14> The compound according to <7> or <8>, wherein, in Formula (2), R² is a sec-butyl group.

<15> The compound according to <7> or <8>, wherein, in Formula (2), R² is a 3-methylbutan-2-yl group.

<16> The compound according to <7> or <8>, wherein, in Formula (2), R² is a cyclopentyl group.

Advantageous Effects of Invention

According to the present invention, it is possible to provide an isobutyric ester compound having a propanoyloxy group at the α-position, useful as a fragrance and a fragrance ingredient. Further, according to the present invention, it is possible to provide a fragrance composition containing an isobutyric ester compound having a propanoyloxy group at the α-position as an active ingredient and use of the compound as a fragrance.

DESCRIPTION OF EMBODIMENTS [Fragrance Composition and Use]

A fragrance composition of the present invention comprises a compound represented by Formula (1) below as an active ingredient. Furthermore, use of the present invention is use of the compound represented by Formula (1) below as a fragrance.

The present invention will be described in detail hereinbelow.

<Compound Represented by Formula (1)>

The compound to be used in the fragrance composition of the present invention and the use of the present invention is represented by Formula (1) below:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

In Formula (1), specific examples of R¹ include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group (2-methylpropyl group), a sec-butyl group (1-methylpropyl group), a tert-butyl group, a n-pentyl group, a 1-methylbutyl group (2-pentyl group), a 2-methylbutyl group, a 3-methylbutyl group, a neopentyl group (2,2-dimethylpropyl group), a 2-methylbutan-2-yl group, a 1-ethylpropyl group (3-pentyl group), a 3-methylbutan-2-yl group, a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group.

When the R¹ group has an asymmetric carbon, the compound represented by Formula (1) includes any one of optical isomers resulting from the asymmetric carbon or a mixture of the isomers at any proportion.

The compound represented by Formula (1), which is useful as a fragrance and a fragrance ingredient, has a mint-like aroma as well as simultaneously exhibits an aroma of a woody tone, spicy tone, floral tone, or the like due to the difference in the alkyl groups (R¹) of the ester moiety.

The compound is preferably a compound in which R¹ is selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group. The compound is also preferably a compound in which R¹ is selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, and a cyclopentyl group.

Particularly preferably, R¹ is a methyl group.

Particularly preferably, R¹ is an ethyl group.

Particularly preferably, R¹ is a n-propyl group.

Particularly preferably, R¹ is an isopropyl group.

Particularly preferably, R¹ is a n-butyl group.

Particularly preferably, R¹ is an isobutyl group.

Particularly preferably, R¹ is a sec-butyl group.

Particularly preferably, R¹ is a 3-methylbutan-2-yl group.

Particularly preferably, R¹ is a cyclopentyl group.

In an embodiment of the present invention, examples of the compound represented by Formula (1) include a compound represented by any of Formulas (1-1) to (1-19) below, and particularly preferable compounds include a compound represented by any of Formulas (1-1) to (1-8), and (1-18) below.

In recent years, there is a trend to focus more on the toxicity and environmental impact of chemicals, and fragrances or fragrance compositions are no exception. There is an increase in the number of cases where a fragrance which has been used in the past is severely restricted in usage conditions or is prohibited from use due to their sensitization properties to a human body, tendency to accumulate in the environment, and the like. Thus, there is a strong demand for a fragrance and a fragrance composition having a lower environmental impact. Accordingly, the fragrance ingredient preferably has excellent biodegradability.

The compound represented by Formula (1) contains a compound excellent in biodegradability, and from the perspective of biodegradability, R¹ is preferably a group selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group. Additionally, from the same perspective, R¹ is preferably a group selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, and a cyclopentyl group.

The compound represented by Formula (1) is useful as a fragrance because the compound has an excellent aroma as described below. Generally, a fragrance is rarely used alone, and often used in a fragrance compound (fragrance composition) produced by compounding a plurality of fragrances in accordance with the purpose. The compound represented by Formula (1) is useful as a fragrance (also called a “fragrance ingredient”) to be blended in a fragrance compound (fragrance composition), and the fragrance composition of the present invention contains the compound represented by Formula (1) as an active ingredient. As the fragrance, one of the compounds represented by Formula (1) above may be used alone or two or more of the compounds may be used in combination.

Additionally, the compound represented by Formula (1) may include a small amount of impurities, by-products, contaminants, and the like as long as the effects of the present invention are not compromised.

The compound represented by Formula (1) has a mint-like aroma as well as an aroma of woody-tone, spicy-tone, floral-tone, or like, and also is excellent in diffusivity. Further, the compound represented by Formula (1-4) has a damascone-like fruity-tone, floral-tone, or woody-tone aroma, and also is excellent in diffusivity.

The compound represented by Formula (1) may be used alone as a fragrance and added to various perfumery and cosmetics, healthcare and sanitary materials as well as medicinal supplies, household goods, foods, and the like to thereby impart an aroma thereto. Alternatively, the compound represented by Formula (1) may be mixed with another fragrance ingredient or the like to prepare a fragrance composition (fragrance compound) described below, which may be blended into a variety of products to impart an aroma. Among these, from the perspective of obtaining an intended aroma, it is preferred that the compound represented by Formula (1) be blended in a fragrance composition as a fragrance ingredient to prepare a fragrance composition containing the compound represented by Formula (1) as an active ingredient and the fragrance composition be blended in a product to perfume the product.

Additionally, the compound represented by Formula (1) is preferably used as a fragrance and is more preferably used to impart a mint-like scent. Furthermore, the compound represented by Formula (1-4) is more preferably used to impart a damascone-like fruity-tone, floral-tone, or woody-tone scent.

<Fragrance Composition>

The fragrance composition (fragrance compound) of the present invention contains the compound represented by Formula (1) as an active ingredient. Note that the fragrance composition is not particularly limited as long as that it contains at least one compound represented by Formula (1), and two or more compounds represented by Formula (1) may be included.

The fragrance composition according to an embodiment of the present invention is only required to contain the compound represented by Formula (1) as an active ingredient, and other ingredients are not particularly limited. However, the fragrance composition preferably contains another fragrance ingredient (hereinafter, also referred to as a “known fragrance”).

Note that the “fragrance composition (fragrance compound)” is a composition that is added to various perfumery and cosmetics, medicinal supplies, foods, beverages, and the like to impart an aroma thereto, or a composition that is used as it is in a perfume or the like. The fragrance composition may contain an additive such as a solvent, as required, in addition to the known fragrance.

The amount of the compound represented by Formula (1) blended depends on the type of the compound, the type of aroma intended, the intensity of the aroma, and the like. The amount of the compound represented by Formula (1) in the fragrance composition is preferably 0.001 mass % or greater, more preferably 0.01 mass % or greater, even more preferably 0.1 mass % or greater, and preferably 90 mass % or less, more preferably 70 mass % or less, and even more preferably 50 mass % or less.

The known fragrance is not particularly limited as long as it is a known fragrance component, and a wide range of fragrances can be used. For example, one or two or more of the following fragrances can be selected and used at any mixing ratio.

Examples thereof include hydrocarbons such as limonene, α-pinene, β-pinene, terpinene, cedrene, longifolene, and valencene; alcohols such as linalool, citronellol, geraniol, nerol, terpineol, dihydromyrcenol, ethyllinalool, farnesol, nerolidol, cis-3-hexenol, cedrol, menthol, borneol, β-phenylethyl alcohol, benzyl alcohol, phenyl hexanol, 2,2,6-trimethylcyclohexyl-3-hexanol, 1-(2-t-butylcyclohexyloxy)-2-butanol, 4-isopropylcyclohexane methanol, 4-t-butylcyclohexanol, 4-methyl-2-(2-methylpropyl)tetrahydro-2H-pyran-4-ol, 2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-butene-1-ol, 2-ethyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-ol, isocamphylcyclohexanol, and 3,7-dimethyl-7-methoxyoctane-2-ol; phenols such as eugenol, thymol, and vanillin; esters such as linalyl formate, citronellyl formate, geranyl formate, n-hexyl acetate, cis-3-hexenyl acetate, linalyl acetate, citronellyl acetate, geranyl acetate, neryl acetate, terpinyl acetate, nopyl acetate, bornyl acetate, isobronyl acetate, o-t-butylcyclohexyl acetate, p-t-butylcyclohexyl acetate, tricyclodecenyl acetate, benzyl acetate, styralyl acetate, cinnamyl acetate, dimethylbenzylcarbinyl acetate, 3-pentyltetrahydropyran-4-yl acetate, citronellyl propionate, tricyclodecenyl propionate, allylcyclohexyl propionate, ethyl-2-cyclohexyl propionate, benzyl propionate, citronellyl butyrate, dimethylbenzylcarbinyl n-butyrate, tricyclodecenyl isobutyrate, methyl-2-nonenoate, methyl benzoate, benzyl benzoate, methyl cinnamate, methyl salicylate, n-hexyl salicylate, cis-3-hexenyl salicylate, geranyl tiglate, cis-3-hexenyl tiglate, methyl jasmonate, methyldihydro jasmonate, methyl-2,4-dihydroxy-3,6-dimethyl benzoate, ethylmethylphenyl glycidate, methyl anthranilate, and FRUITATE; aldehydes such as n-octanal, n-decanal, n-dodecanal, 2-methylundecanal, 10-undecenal, citronellal, citral, hydroxycitronellal, dimethyl tetrahydrobenzaldehyde, 4(3)-(4-hydroxy-4-methylpentyl)-3-cyclohexene-1-carboaldehyde, 2-cyclohexyl propanal, p-t-butyl-α-methylhydrocinnamic aldehyde, p-isopropyl-α-methylhydrocinnamic aldehyde, p-ethyl-α,α-dimethylhydrocinnamic aldehyde, α-amylcinnamic aldehyde, α-hexylcinnamic aldehyde, piperonal, and α-methyl-3,4-methylenedioxyhydrocinnamic aldehyde; ketones such as methylheptenone, 4-methylene-3,5,6,6-tetramethyl-2-heptanone, amylcyclopentanone, 3-methyl-2-(cis-2-pentene-1-yl)-2-cyclopentene-1-on, methylcyclopentenolone, rose ketones, γ-methylionone, α-ionone, carbone, menthone, camphor, nootkatone, benzylacetone, anisylacetone, methyl-β-naphthylketone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, maltol, 7-acetyl-1,2,3,4,5,6,7,8-octahydro-1,1,6,7-tetramethyl naphthalene, muscone, civetone, cyclopentadecanone, and cyclohexedecanone; acetals and ketals such as acetoaldehyde ethylphenylpropyl acetal, citraldiethyl acetal, phenylacetoaldehyde glycerin acetal, and ethylacetoacetate ethyleneglycol ketals; ethers such as anethole, Q-naphthylmethyl ether, β-naphthylethyl ether, limonene oxide, rose oxide, 1,8-cineol, and racemic or photoactive dodecahydro-3a,6,6,9α-tetramethylnaphtho[2, 1-b]furane; nitriles such as citronellyl nitrile; lactones such as γ-nonalactone, γ-undecalactone, α-decalactone, γ-jasmolactone, coumarin, cyclopentadecanolide, cyclohexadecanolide, ambrettolide, ethylene brassylate, and 11-oxahexadecanolide; natural essential oils and natural extracts of orange, lemon, bergamot, mandarin, peppermint, spearmint, lavender, chamomile, rosemary, eucalyptus, sage, basil, rose, geranium, jasmine, ylang-ylang, anise, clove, ginger, nutmeg, cardamom, cedar, Japanese cypress, sandalwood, vetiver, patchouli, and labdanum; and other fragrance materials such as synthetic fragrances.

In addition, the fragrance composition may also contain, as components besides the fragrance ingredients, a surfactant such as polyoxyethylene lauryl sulfate ether; a solvent such as dipropylene glycol, diethyl phthalate, ethylene glycol, propylene glycol, methyl myristate, triethyl citrate, or the like; an antioxidant; a coloring agent, and the like.

The compound represented by Formula (1), which has a mint-like aroma and simultaneously has an aroma of a woody note, a spicy note, a floral note, or the like, can impart a natural woody note, a spicy note, or a floral note in addition to the mint note when combined with a known fragrance. Thus, the compound is usefully added to various perfumery and cosmetics, healthcare and sanitary materials as well as to medicinal supplies, household goods, foods, and the like to thereby impart an aroma thereto. The isobutyric ester according to an embodiment of the present invention represented by Formula (1-4) is usefully combined with a known fragrance or the like to thereby impart an aroma because of having a damascone-like fruity-tone, floral-tone, or woody-tone aroma.

Examples of products to which a fragrance composition containing the compound represented by Formula (1) can be added to impart an aroma and improve the aroma of the blend object include various products such as perfumery and cosmetics, health and sanitary materials, miscellaneous goods, beverages, foods, quasi-pharmaceutical products, and medicinal supplies; the fragrance composition can be used as an aroma component in, for example, fragrance products such as perfumes and colognes; hair cosmetics such as shampoos, rinses, hair tonics, hair creams, mousses, gels, pomades, sprays, and the like; skin cosmetics such as skin lotions, essences, creams, milky lotions, packs, foundations, face powders, lipsticks, and various make-up products; various health and sanitary detergents such as dish washing detergents, laundry detergents, softeners, disinfecting detergents, anti-odor detergents, indoor fragrances, furniture cares, glass cleaners, furniture cleaners, floor cleaners, disinfectants, insecticides, bleaching agents, bactericides, repellants, and the like; quasi-pharmaceutical products such as toothpastes, mouthwashes, bath additives, antiperspirant products, and perming liquids; miscellaneous goods such as toilet paper and tissue paper; medicinal supplies; foods, and the like.

The amount of the fragrance composition blended in the product is not particularly limited, and the amount of the fragrance composition blended can be selected over a wide range, depending on the type, nature, and sensory benefits of the product to be perfumed. For example, the amount may be 0.00001 mass % or greater, preferably 0.0001 mass % or greater, and more preferably 0.001 mass % or greater. In the case of a fragrance such as perfume or the like, for example, the amount may be 100 mass %, preferably 80 mass % or less, more preferably 60 mass % or less, and even more preferably 40 mass % or less.

[Compound Represented by Formula (2)]

A compound according to an embodiment of the present invention is represented by Formula (2). The compound represented by Formula (2) below is also referred to as the “isobutyric ester according to an embodiment of the present invention” or the “compound according to an embodiment of the present invention”.

wherein, in Formula (2), R² represents a linear, branched, or cyclic alkyl group having 2 to 5 carbon atoms.

In Formula (2), specific examples of R² include an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group (2-methylpropyl group), a sec-butyl group (1-methylpropyl group), a tert-butyl group, a n-pentyl group, a 1-methylbutyl group (2-pentyl group), a 2-methylbutyl group, a 3-methylbutyl group, a neopentyl group (2,2-dimethylpropyl group), a 2-methylbutan-2-yl group, a 1-ethylpropyl group (3-pentyl group), a 3-methylbutan-2-yl group, a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group.

When the R² group has an asymmetric carbon, the compound represented by Formula (2) comprises any one of optical isomers resulting from the asymmetric carbon or a mixture of the isomers at any proportion.

For the isobutyric ester according to an embodiment of the present invention, in Formula (2), R² is preferably selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group. Additionally, R² is also preferably selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, and a cyclopentyl group.

That is, the isobutyric ester according to an embodiment of the present invention is particularly preferably the following compound.

In Formula (2), R² is an ethyl group.

In Formula (2), R² is a n-propyl group.

In Formula (2), R² is an isopropyl group.

In Formula (2), R² is a n-butyl group.

In Formula (2), R² is an isobutyl group.

In Formula (2), R² is a sec-butyl group.

In Formula (2), R² is a 3-methylbutan-2-yl group.

In Formula (2), R² is a cyclopentyl group.

A compound preferred as the isobutyric ester according to an embodiment of the present invention is a compound represented by any of Formulas (2-1) to (2-18) below, and particularly preferred is a compound represented by any of Formulas (2-1) to (2-7) or (2-17).

Note that the isobutyric ester according to an embodiment of the present invention is any of compounds represented by Formula (1) excluding methyl α-propanoyloxyisobutyrate, in which R¹ is a methyl group. Thus, the isobutyric ester according to an embodiment of the present invention is useful alone as a fragrance and is also useful as an active ingredient for a fragrance composition.

Additionally, the isobutyric ester according to an embodiment of the present invention is preferably used as a fragrance and is more preferably used to impart a mint-like scent. Furthermore, the isobutyric ester according to an embodiment of the present invention represented by Formula (2-3) is more preferably used to impart a damascone-like fruity-tone, floral-tone, or woody-tone fragrance.

[Method for Producing Isobutyric Ester According to Embodiment of Present Invention and Compound Represented by Formula (1)]

The production method of the isobutyric ester according to an embodiment of the present invention represented by Formula (2) and the compound represented by Formula (1) is not particularly limited and may be appropriately selected from known methods and used.

Examples thereof include a method including reacting an α-hydroxyisobutyric ester with an acylating agent in the presence or absence of a catalyst to propanoylate the hydroxyl group at the α-position. Examples of the acylating agent to be used include carboxylic acids such as propionic acid, carboxylic anhydrides such as propionic anhydride, carboxylic halides such as propanoyl chloride and propanoyl bromide, and ketene compounds such as methyl ketene. In addition, two or more acylating agents selected from these may be used in combination at any ratio.

The reaction formula when a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid halide is used is shown as Formula (3) below.

In Formula (3), R represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms. Y depends on the type of the acylating agent and represents, for example, a hydroxyl group, a propanoyloxy group, chlorine, bromine, iodine, or the like.

The reaction formula when a ketene compound is used is shown as Formula (4) below.

In Formula (4), R represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

Further, a target α-propanoyloxyisobutyric ester can be produced by transesterifying an α-propanoyloxyisobutyric ester with an alcohol of different kinds in the presence of a catalyst. The reaction formula for this reaction is shown as Formula (5) below.

In Formula (5), R represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms. R′ is not particularly limited as long as it is an alkyl group different from R.

Similarly, a target α-propanoyloxyisobutyric ester can be produced by esterifying α-propanoyloxyisobutyric acid with an alcohol in the presence of a catalyst. The reaction formula for this reaction is shown as Formula (6) below.

In Formula (6), R represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

Known catalysts, reaction methods, reaction conditions, and reaction apparatus can be used as the catalyst, reaction method, reaction conditions, reaction apparatus, and the like to be used for these reactions, and there are no particular limitation thereon. In addition, as a method for purifying the isobutyric ester according to an embodiment of the present invention represented by Formula (2) and the compound represented by Formula (1) obtained, a known purification method can be used, and there is no limitation thereon.

EXAMPLES

Hereinafter, the present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples.

The reaction performance was evaluated according to the following expression.

Reaction yield (%)=[(number of moles of product ester in reaction solution)/(number of moles of raw material ester in solution fed)]×100%

<Gas Chromatography (GC) Analysis Conditions>

Apparatus: GC-2010 (available from Shimadzu Corporation, trade name)

Detector: FID

Column: DB-1 (capillary column available from J&W Scientific, Inc., trade name) (0.25 mmφ×60 m×0.25 μm)

<NMR Spectrum Analysis>

Identification of the ester was performed by ¹H-NMR measurement and ¹³C-NMR measurement. The measurement conditions are shown below.

Apparatus: ECA500 (available from JEOL Ltd., trade name)

[¹H-NMR]

Nuclide: ¹H

Measurement frequency: 500 MHz

Measurement sample: 5% CDCl₃ solution

[¹³C-NMR]

Nuclide: ¹³C

Measurement frequency: 125 MHz

Measurement sample: 5% CDCl₃ solution

<Gas Chromatograph-Mass Spectrometry (GC-MS Analysis)>

Identification of the compounds was also performed by determining the molecular weight by GC-MS measurement (chemical ionization method [CI+], high resolution mass spectrometry [millimass]). The measurement conditions are shown below.

GC apparatus: Agilent 7890A (available from Agilent Technologies, trade name)

GC measurement conditions

Column: DB-1 (capillary column available from J&W Scientific, Inc., trade name) (0.25 mmφ×30 m×0.25 μm)

MS apparatus: JMS-T100GCV (available from JEOL Ltd., trade name)

MS measurement conditions: chemical ionization method

Detector conditions: 200 eV, 300 μA

Reagent gas: isobutane

The exact mass values of fragments detected in the protonated state by the chemical ionization method and the chemical composition formula thus attributed were described.

Example 1: Synthesis of Methyl α-Propanoyloxyisobutyrate

20.0 g of methyl α-hydroxyisobutyrate (available from Mitsubishi Gas Chemical Company, Inc.), 26.4 g of propionic anhydride (available from Wako Pure Chemical Industries, Ltd.), 13.4 g of pyridine (available from Wako Pure Chemical Industries, Ltd.), and 2.1 g of 4-dimethylaminopyridine (available from Wako Pure Chemical Industries, Ltd.) were loaded in a 200 mL glass round bottom flask equipped with a condenser and a stirrer, and reacted under stirring at room temperature for 24 hours. From the GC analysis of the reaction solution, it was confirmed that methyl α-hydroxyisobutyrate was completely consumed by the reaction with propionic anhydride and that methyl α-propanoyloxyisobutyrate was obtained at a reaction yield of 96% by the reaction of Formula (7) below. Then, a washing operation was performed three times with a 10% aqueous solution of sodium hydrogen carbonate and twice with a saturated aqueous solution of sodium chloride. The washed product was dried over magnesium sulfate and then concentrated. Subsequently, distillation was performed under reduced pressure to obtain 22.7 g of methyl α-propanoyloxyisobutyrate (purity by GC analysis (hereinafter, also referred to as GC purity): 99.6%) as the fraction at 70 hPa and 107° C.

Reference Example 1: Synthesis of Ethyl α-Hydroxyisobutyrate

In a 300 mL glass flask equipped with a distillation tube, 56.7 g of methyl α-hydroxyisobutyrate (available from Mitsubishi Gas Chemical Company, Inc.), 33.2 g of ethanol (available from Wako Pure Chemical Industries, Ltd.), and 0.92 g of titanium tetraethoxide (available from Wako Pure Chemical Industries, Ltd.) were loaded. A transesterification reaction was performed under normal pressure with heating and refluxing. The reaction was performed for 96 hours while methanol produced was extracted out of the system. As a result, ethyl α-hydroxyisobutyrate was obtained at a reaction yield of 97%. After water was added to the reaction system to inactivate the catalyst, distillation was performed under reduced pressure to obtain 46.9 g of ethyl α-hydroxyisobutyrate (GC purity: 99.6%) as the fraction at 71 mmHg and 77° C.

Reference Examples 2 to 8: Synthesis of Various α-Hydroxyisobutyric Esters

Using the same reaction apparatus as in Reference Example 1, an appropriate amount of methyl α-hydroxyisobutyrate (available from Mitsubishi Gas Chemical Company, Inc.) was transesterified with a different alcohol (n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, 3-methyl-2-butanol, cyclopentanol) in the presence of a suitable catalyst such as a titanium tetraalkoxide and/or sodium alkoxide, and in some cases in the co-presence of a solvent such as hexane or toluene, under appropriate reaction conditions with heating. The transesterification reaction was completed while methanol produced by the reaction was extracted out of the system by distillation or through azeotrope with a reaction solvent under the reaction conditions. The same separation operation as in Reference Example 1 was performed to obtain each of the following α-hydroxyisobutyric ester. The GC purity of the obtained isobutyric ester is also shown.

n-Propyl α-hydroxyisobutyrate (GC purity: 99.8%)

Isopropyl α-hydroxyisobutyrate (GC purity: 99.6%)

n-Butyl α-hydroxyisobutyrate (GC purity: 99.9%)

Isobutyl α-hydroxyisobutyrate (GC purity: 99.6%)

sec-Butyl α-hydroxyisobutyrate (GC purity: 99.6%)

3-Methylbutan-2-yl α-hydroxyisobutyrate (GC purity: 99.7%)

Cyclopentyl α-hydroxyisobutyrate (GC purity: 99.8%)

Example 2: Synthesis of Ethyl α-Propanoyloxyisobutyrate

Using a reaction apparatus similar to that of Example 1, a reaction was performed using ethyl α-hydroxyisobutyrate prepared in Reference Example 1, propionic anhydride (available from Wako Pure Chemical Industries, Ltd.), pyridine (available from Wako Pure Chemical Industries, Ltd.), and 4-dimethylaminopyridine (available from Wako Pure Chemical Industries, Ltd.) in appropriate amounts. The operation was performed in the same manner as in Example 1 to obtain ethyl α-propanoyloxyisobutyrate (GC purity: 99.6%) as the fraction at 40 hPa and 102° C. by distillation under reduced pressure. The results of the NMR spectral analysis and GC-MS analysis of the product are shown below.

[Ethyl α-Propanoyloxyisobutyrate]

¹H NMR (500 MHz, CDCl₃) δ 1.14 (3H, t, J=7.5 Hz), 1.25 (3H, t, J=7.0 Hz), 1.55 (6H, s), 2.33 (2H, q, J=7.5 Hz), 4.18 (2H, q, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 14.0, 24.6, 27.6, 61.2, 78.0, 172.7, 173.4

Exact. Mass 189.12087 (C₉H₁₆O₄, parent peak), 143.06928 (C₇H₁₀O₃)

Examples 3 to 9: Synthesis of α-Propanoyloxyisobutyric Ester

Using a reaction apparatus similar to that of Example 2, a reaction was performed using each α-hydroxyisobutyric ester prepared in Reference Examples 2 to 8, propionic anhydride (available from Wako Pure Chemical Industries, Ltd.), pyridine (available from Wako Pure Chemical Industries, Ltd.), and 4-dimethylaminopyridine (available from Wako Pure Chemical Industries, Ltd.) in appropriate amounts. The operation was performed in the same manner as in Example 1 to obtain each of α-propanoyloxyisobutyric esters described below by distillation under reduced pressure. The GC purity of the resulting esters, the distillation conditions during the distillation under reduced pressure, and the results of NMR spectral analysis and GC-MS analysis are also shown.

[n-Propyl α-Propanoyloxyisobutyrate]

GC purity: 98.3%, distillation condition: 29 hPa, 107° C.

¹H NMR (500 MHz, CDCl₃) δ 0.94 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5 Hz), 1.55 (6H, s), 1.62-1.69 (2H, m), 2.33 (2H, q, J=7.5 Hz), 4.08 (2H, t, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 10.3, 21.8, 24.6, 27.6, 66.7, 78.0, 172.7, 173.3

Exact. Mass 203.13216 (C₁₀H₁₈O₄, parent peak), 143.07371 (C₇H₁₀O₃)

[Isopropyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%, distillation condition: 40 hPa, 103° C.

¹H NMR (500 MHz, CDCl₃) δ 1.14 (3H, t, J=7.5 Hz), 1.23 (6H, d, J=6.5 Hz), 1.53 (6H, s), 2.32 (2H, q, J=7.5 Hz), 5.03 (1H, sept, J=6.5 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 21.5, 24.5, 27.6, 68.5, 78.0, 172.1, 173.3

Exact. Mass 203.13301 (C₁₀H₁₈O₄, parent peak), 143.07356 (C₇H₁₀O₃)

[n-Butyl α-Propanoyloxyisobutyrate]

GC purity: 99.5%, distillation condition: 13 hPa, 101° C.

¹H NMR (500 MHz, CDCl₃) δ 0.93 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5 Hz), 1.34-1.43 (2H, m), 1.55 (6H, s), 1.58-1.64 (2H, m), 2.33 (2H, q, J=7.5 Hz), 4.12 (2H, t, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 13.6, 19.0, 24.6, 27.6, 30.4, 65.0, 78.0, 172.7, 173.3

Exact. Mass 217.15016 (C₁₁H₂₀O₄, parent peak), 143.07245 (C₇H₁₀O₃)

[Isobutyl α-Propanoyloxyisobutyrate]

GC purity: 99.4%, distillation condition: 19 hPa, 106° C.

¹H NMR (500 MHz, CDCl₃) δ 0.93 (6H, d, J=6.5 Hz), 1.13 (3H, t, J=7.5 Hz), 1.56 (6H, s), 1.94 (1H, m), 2.34 (2H, q, J=7.5 Hz), 3.90 (2H, d, J=6.5 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 19.0, 24.7, 27.60, 27.63, 71.2, 78.0, 172.7, 173.3

Exact. Mass 217.14776 (C₁₁H₂₀O₄, parent peak), 143.07242 (C₇H₁₀O₃)

[Sec-Butyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%

¹H NMR (500 MHz, CDCl₃) δ 0.90 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5 Hz), 1.20 (3H, d, J=6.0 Hz), 1.51-1.58 (2H, m), 1.55 (3H, s), 1.55 (3H, s), 2.32 (2H, q, J=7.5 Hz), 4.87 (1H, sext, J=6.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 9.5, 19.1, 24.5, 24.6, 27.6, 28.6, 73.1, 78.1, 172.2, 173.2

Exact. Mass 217.14670 (C₁₁H₂₀O₄, parent peak), 203.13175 (C₁₀H₁₈O₄)

[3-Methylbutan-2-Yl α-Propanoyloxyisobutyrate]

GC purity: 98.7%

¹H NMR (500 MHz, CDCl₃) δ 0.904 (6H, d, J=6.5 Hz), 1.131 (3H, t, J=7.75 Hz), 1.152 (3H, d, J=6.0 Hz), 1.541 (3H, s), 1.552 (3H, s), 1.796 (1H, septd, J=6.88 Hz, 6.0 Hz), 2.327 (2H, q, J=7.5 Hz), 4.760 (1H, qd, J=6.0 Hz, 6.25 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.12, 16.42, 17.91, 18.18, 24.64, 24.90, 27.78, 32.70, 76.23, 78.30, 172.34, 173.36

Exact. Mass 231.16135 (C₁₂H₂₂O₄, parent peak), 161.08692 (C₇H₁₂O₄)

[Cyclopentyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%, distillation condition: 9 hPa, 111° C.

¹H NMR (500 MHz, CDCl₃) δ 1.13 (3H, t, J=7.5 Hz), 1.53 (6H, s), 1.58-1.63 (2H, in), 1.67-1.74 (4H, in), 1.78-1.86 (2H, in), 2.32 (2H, q, J=7.5 Hz), 5.19 (1H, m)

¹³C NMR (125 MHz, CDCl₃) δ 23.6, 24.5, 27.6, 32.3, 78.0 (×2C), 172.3, 173.2

Exact. Mass 229.14540 (C₁₂H₂₀O₄, parent peak), 1610.08500 (C₇H₁₂O₄)

The results of aroma evaluation performed by perfumers for the various α-propanoyloxyisobutyric esters obtained by the method described above are shown in Table 1.

TABLE 1 Structural formula Aroma evaluation Example 1

Mint-like aroma having a refreshing feeling Woody aroma Clove-like spicy aroma Example 2

Brisk mint-like aroma Spicy aroma Basil-like herbal green aroma Earthy aroma Example 3

Brisk mint-like aroma Anise-like aroma Spicy aroma White floral aroma Example 4

Fresh mint-like aroma Spicy rose-like aroma Fruity and rose-like floral aroma (damascone-like) Example 5

Fresh mint-like aroma Citronella-like aroma Spicy herbal green aroma Sweet white floral aroma Example 6

Fresh mint-like aroma Sweet coconut-like aroma Citronella-like aroma Lilac-like floral aroma Example 7

Rose-like and hyacinth-like green aroma Rose-like floral aroma Mint-like aroma Example 8

Rose-like and muguet-like floral aroma White floral aroma Lime-like green aroma Mint-like aroma having a refreshing feeling Example 9

Fresh mint-like aroma Myrrha-based rose-like floral aroma Green apple-like fruity aroma Green aroma

<Biodegradability Evaluation of Fragrance Material>

One of methods for evaluating biodegradability of a compound is the OECD test guideline 301 C. In accordance with the method, assessment of biodegradability is possible for the compound from the biochemical oxygen demand and the actual rate of oxygen uptake in an aqueous solution in which the compound and aerobic microorganisms coexist.

Calculation software “Biowin5” and “Biowin6” is known and used in a method for easily and accurately estimating the probability of biodegradation of the compound in compliance with this test method.

The software is available to the public as one of modules of calculation software called “The Estimations Programs Interface for Windows version 4.1”, created by the United States Environmental Protection Agency (EPA) for the purpose of evaluating the environmental effects of chemical substances, and is used in the compound classification for The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and the review of new chemical substances by the United States Environmental Protection Agency. This software was used to evaluate the difference in biodegradability between existing fragrance materials and the compounds according to an embodiment of the present invention.

Menthol, menthone, and carvone, having a mint note and (E)-α-damascone and (E)-β-damascenone, having a fruity note, were selected as representative examples of existing fragrance materials similar to the compounds according to an embodiment of the present invention, and evaluated along with the compounds according to an embodiment of the present invention. The SMILES formulas used for input to the software and the output results of the probabilities of good degradability by “Biowin5 (linear prediction model)” and “Biowin6 (non-linear prediction model)” are shown in Tables 2 to 3. A larger value of the results indicates better degradability: for a value of 0.5 or greater, the compound was rated as having good degradability (symbol “A” in the table), and for a value of less than 0.5, the compound was rated as having low degradability (symbol “B” in the table).

From Table 2 to Table 3, the results obtained show that the compounds according to an embodiment of the present invention were expected to have good biodegradability with respect to menthol, menthone, carvone, (E)-α-damascone, and (E)-β-damascenone, which were the existing fragrance materials similar to the compounds according to an embodiment of the present invention. The results indicated that the compounds according to an embodiment of the present invention are easily biodegraded after being released into the environment as fragrances, and thus exhibited a lower impact on the environment.

TABLE 2 Biowin5 Biowin6 Degradation Degradation Examples Structural formula SMILES probability Score probability Score 1

COC(C(C)(C)OC(CC)═O)═O 1.000 A 0.964 A 2

CC(C(OCC)═O)(C)OC(CC)═O 1.008 A 0.965 A 3

CC(C(OCCC)═O)(C)OC(CC)═O 1.015 A 0.966 A 4

CC(C(OC(C)C)═O)(C)OC(CC)═O 0.866 A 0.917 A 5

CC(C(OCCCC)═O)(C)OC(CC)═O 1.023 A 0.967 A 6

CC(C(OCC(C)C)═O)(C)OC(CC)═O 0.874 A 0.919 A 7

CC(C(OC(C)CC)═O)(C)OC(CC)═O 0.874 A 0.919 A 8

CC(C(OC(C)C(C)C)═O)(C)OC(CC)═O 0.733 A 0.820 A 9

CC(C(OC1CCCC1)═O)(C)OC(CC)═O 0.930 A 0.926 A

TABLE 3 Biown5 Biown6 Comparative Degradation Degradation Example Structural formula SMILES probability Score probability Score 1

CC(C)C1CCC(C)CC1O 0.455 B 0.331 B 2

CC(C)C1CCC(C)CC1═O 0.406 B 0.335 B 3

C═C(C)C(C1)CC═C(C)C1═O 0.454 B 0.375 B 4

CC1(C)C(C(/C═C/C)═O)C(C)═CCC1 0.398 B 0.216 B 5

CC1(C)C(C(/C═C/C)═O)C(C)C═CC1 0.378 B 0.213 B

Example 10: Woody-Type Fragrance Composition

A fragrance composition was prepared by adding 37.0 parts by mass of the methyl α-propanoyloxyisobutyrate obtained in Example 1 to 63.0 parts by mass of a fragrance composition having a composition shown in Table 4.

According to the aroma evaluation by perfumers, addition of the methyl α-propanoyloxyisobutyrate of Example 1 to the fragrance composition having the composition described in Table 4 added a volume and strength to the scent, lifted up the citrus, and improved the integrity. As a result, provided was an elegant woody-note fragrance composition having a brisk and fresh citrus mint nuance, to which a mint-like refreshing feeling, woodiness, and spiciness were imparted. The aroma of this fragrance composition seems to be suitable for perfuming aftershave lotion, men's skin cream, and the like.

TABLE 4 parts by Blend ingredients mass D-Limonene 32.1 Linalool 14.3 Decanal (2%) (C-10) 2.9 Lemon oil 2.3 Cyclopentadecanone (10%) 2.0 Lavender oil 1.4 10-Undecanal (2%) 1.3 Ambroxide (5%) 1.3 Oakmoss absolute (10%) 1.3 Lilial (50%) 0.8 Styralyl acetate (10%) 0.8 4-Isopropylcyclohexanol (10%) 0.7 Geranium oil (50%) 0.7 Dimethol (50%) 0.7 Coumarin 0.6 Total 63.0 *Blend ingredients in parentheses in the table were used as a solution diluted with dipropylene glycol. The figures represent mass % of the fragrance included in the solution.

Example 11: White Floral-Type Fragrance Composition

A fragrance composition was prepared by adding 21.0 parts by mass of the n-propyl α-propanoyloxyisobutyrate obtained in Example 3 to 79.0 parts by mass of a fragrance composition having a composition shown in Table 5.

According to the aroma evaluation by perfumers, addition of the n-propyl α-propanoyloxyisobutyrate of Example 3 to the fragrance composition having the composition described in Table 5 improved the integrity, increased the stability, and enhanced the intensity of the scent. As a result, provided was a fragrance composition having a soft and clean white floral aroma, to which brisk mint-like, soft anise-like, and warm spiciness was imparted. The aroma of this fragrance composition seems to be suitable for perfuming milky lotion, skin cream, body lotion, and the like.

TABLE 5 parts by Blend ingredients mass Hydroxycitronellal 19.5 Phenethyl alcohol 16.8 Cyclopentadecanone 11.5 α, α-Dimethylbenzylcarbinol 9.7 α-Methyl-1,3-benzodioxole-5-propanal 6.2 Hexyl salicylate 5.4 Linalool 4.6 α-Terpineol 4.1 α-Ionone 1.1 Total 79.0

INDUSTRIAL APPLICABILITY

An isobutyric ester compounds having a propanoyloxy group at the α-position according to an embodiment of the present invention has an excellent aroma and is expected to be used itself as a fragrance. Additionally, use of the compound as a fragrance ingredient can provide a fragrance composition excellent in aroma properties. The composition, when blended in a variety of products, exhibits desired perfuming properties.

Furthermore, it was shown that the compounds obtained in Examples each have excellent biodegradability and a low impact on the environment and are suitable for use. 

1. A fragrance composition comprising a compound represented by Formula (1) as an active ingredient:

wherein, in Formula (1), R¹ represents a straight, branched, or cyclic alkyl group having from 1 to 5 carbon atoms.
 2. The fragrance composition according to claim 1, wherein, in Formula (1), R¹ is selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group. 3-6. (canceled)
 7. A compound, represented by Formula (2):

wherein, in Formula (2), R² represents a straight, branched, or cyclic alkyl group having 2 to 5 carbon atoms.
 8. The compound according to claim 7, wherein, in Formula (2), R² is selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.
 9. The compound according to claim 7, wherein, in Formula (2), R² is an ethyl group.
 10. The compound according to claim 7, wherein, in Formula (2), R² is a n-propyl group.
 11. The compound according to claim 7, wherein, in Formula (2), R² is an isopropyl group.
 12. The compound according to claim 7, wherein, in Formula (2), R² is a n-butyl group.
 13. The compound according to claim 7, wherein, in Formula (2), R² is an isobutyl group.
 14. The compound according to claim 7, wherein, in Formula (2), R² is a sec-butyl group.
 15. The compound according to claim 7, wherein, in Formula (2), R² is a 3-methylbutan-2-yl group.
 16. The compound according to claim 7, wherein, in Formula (2), R² is a cyclopentyl group. 